1. Field of the Invention
This invention relates in general to a device and method for determining where a person is looking and more specifically involves analysis of a digitized image of the person's eye to determine the location and orientation of the iris or pupil in the image to determine an optical axis vector for that eye.
2. Description of the Related Art
The majority of patents in this area describe computer input devices for users who are physically handicapped. Most of these devices are based upon use of an infrared-sensitive image sensor and a collimated infrared source. The position of the subject's pupil (in the sensor's image frame) with respect to a corneal "glint" provides an estimate of the visual axis for one of the subject's eyes. An initial calibration procedure, during which the subject is asked to fix his gaze upon certain "known" points, reduces the error estimate to an acceptable level for subsequent operation.
Another technique initially maps surface veins on the retina (of one of the subject's eyes) through the pupillary opening and then tracks those portions of the map revealed through the pupil as the subject looks around.
Other methodologies depicted in the art are less practical than these and range from the merely cumbersome to the highly improbable. Regardless, none of the prior art methods is particularly precise or reliable.
This patent describes a point-of-gaze tracker which achieves improved precision and reliability by tracking the optical axes of both eyes in a novel way.